A keloid is a fibrous new growth that, to all intents and purposes, is simply a hypertrophic scar. They are not especially common in whites, but are very frequently encountered in the negro. In former years it was believed that there were two varieties of keloid-the false, which arose as the result of trauma, and the true, which originated in a healthy skin. It is now generally conceded, however, that all keloids are the result of some injury, although it is by no means understood why the overgrowth of fibrous tissue should oc-«ur. Keloids may be single or multiple, and they may be very small or they may reach the diameter of 6 or even more inches. They may be either sessile or pedunculated. The growth is very hard and firm, and usually distinctly rounded, in addition to being definitely encapsulated. Keloids are devoid of hair.
Pathologically, the condition has been most carefully studied by Heidingsfeld,* who found that all hypertrophic scars and keloids were of similar structure, and composed of dense bands of fibrous tissue, usually running parallel with the surface. The epidermis is usually flattened and thinned. Glands, hair follicles, and muscles are pushed aside, and may be somewhat atrophied. There are but few blood vessels present. As a general rule, keloids do not become malignant, although Anderson* has reported a case where such change did occur. The best treatment for keloids is the x-ray; in fact, it is the only treatment that is at all satisfactory.
*Heidingsfeld: Jour. Amer. Med. Assn., 1909, liii, 1277.
*Adami: "Inflammation," New York, 1907.
The acne keloid, or dermatitis papillaris capillitii, is a collection of small keloidal growths upon the back of the neck and upon the adjoining posterior portion of the scalp. Each papule is pierced by one or several hairs, and there is often pus in the follicles. The condition has recently been carefully studied by Adamson.4 X-ray is the treatment of preference.